docs: def distribution(self, **slice_kwargs):
          """
          Calculates the number of papers in each slice, as defined by
          ``slice_kwargs``.
  
          Examples
          --------
          .. code-block:: python
  
             >>> corpus.distribution(step_size=1, window_size=1)
             [5, 5]
  
          Parameters
          ----------
          slice_kwargs : kwargs
              Keyword arguments to be passed to :meth:`.Corpus.slice`\.
  
          Returns
          -------
          list
          """
          values = []
          keys = []
  
          for key, size in self.slice(count_only=True, **slice_kwargs):
              values.append(size)
              keys.append(key)
          return keys, values